From: Thomas Gleixner <tglx@linutronix.de>
To: John Stultz <johnstul@us.ibm.com>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
Prarit Bhargava <prarit@redhat.com>,
stable@vger.kernel.org
Subject: Re: [PATCH 1/2] [RFC] Fix clock_was_set so it is safe to call from atomic
Date: Mon, 2 Jul 2012 10:53:08 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.02.1207021050500.2793@ionos> (raw)
In-Reply-To: <1341167401-31342-2-git-send-email-johnstul@us.ibm.com>
On Sun, 1 Jul 2012, John Stultz wrote:
> NOTE:This is a prerequisite patch that's required to
> address the widely observed leap-second related futex/hrtimer
> issues.
>
> Currently clock_was_set() is unsafe to be called from atomic
> context, as it calls on_each_cpu(). This causes problems when
> we need to adjust the time from update_wall_time().
>
> To fix this, introduce a work_struct so if we're in_atomic,
> we can schedule work to do the necessary update after we're
> out of the atomic section.
Shouldn't we queue a timer_list timer with expiry time jiffies + 0
instead. We can call on_each_cpu() from softirq context. And that
ensures that the update happens right away, while a scheduled work
might be delayed arbitrary long.
Thanks,
tglx
next prev parent reply other threads:[~2012-07-02 8:53 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-01 18:29 [PATCH 0/2][RFC] Potential fix for leapsecond caused futex issue (v2) John Stultz
2012-07-01 18:30 ` [PATCH 1/2] [RFC] Fix clock_was_set so it is safe to call from atomic John Stultz
2012-07-02 8:53 ` Thomas Gleixner [this message]
2012-07-02 22:11 ` John Stultz
2012-07-01 18:30 ` [PATCH 2/2] [RFC] Fix leapsecond triggered hrtimer/futex load spike issue John Stultz
2012-07-01 18:34 ` [PATCH 0/2][RFC] Potential fix for leapsecond caused futex issue (v2) John Stultz
2012-07-01 18:47 ` Jan Engelhardt
2012-07-01 22:05 ` John Stultz
2012-07-02 4:12 ` John Stultz
2012-07-02 13:53 ` Prarit Bhargava
2012-07-02 18:51 ` Dave Jones
2012-07-02 19:08 ` John Stultz
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